Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 180924
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
324 AM CST Thu Dec 18 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 323 AM CST Thu Dec 18 2014

Vigorous little shortwave over northern Kansas is producing a broad
area of snow over parts of north central Missouri back toward west
central Missouri.  The going forecast looks pretty good in general;
however current radar and latest short range model guidance suggests
that there will be more precipitation across parts of northeast
Missouri and west central Illinois than previously forecast.  Low to
mid level frontogenesis and isentropic lift will increase through
15Z as the wave passes north of the area.  The shortwave should be
dampening out as it moves into an area of longwave ridging, so
precipitation should be on the decline through the morning, and
there is still a wedge of low level dry air to overcome, but
measurable precip does look likely across most of the area.
Accumulations still look pretty light with most areas receiving an
inch or less except for parts of central and southeast Missouri
where an inch or two of wet snow is likely to accumulate.  With
temperatures hovering right around freezing, expect some slick spots
on any untreated roads this morning, but temperatures should be
rising above freezing in most locations by mid to late morning so
that should alleviate any road issues.  Additionally, expect precip
to be winding down pretty rapidly after 15Z as the shortwave dampens
out and the primary band of frontogenesis and isentropic lift
weakens.  The one place where there may be lingering problems is
northeast Missouri and west central Illinois where temperatures may
struggle to break freezing this afternoon.

Carney

.LONG TERM: (Friday through Next Wednesday)
Issued at 231 PM CST Wed Dec 17 2014

Our area may be too far north to receive much precipitation from
the next system to move across the southern part of the US. The
upper trough is forecast to move through MO/AR/LA on Friday night,
but the associated surface low will be hugging the Gulf Coast.
Trended a bit lower and farther south with PoPs for Friday night.

NWP guidance points to additional systems which could bring rain
or snow to the area on Sunday (passage of an upper trough), Sunday
night into Monday (strengthening upstream vort max), and/or the
middle of next week (closed low migrating into northern MO or
southern IA), but there is too much variability attm for much more
than broad-brushed PoPs AOB 40% with RA/SN.

Kanofsky

&&

.AVIATION:  (For the 06z TAFs through 06z Thursday Night)
Issued at 1137 PM CST Wed Dec 17 2014

Snow will move KCOU in the next 1-2 hours and into the St. Louis
metro area TAFs between 9-12Z. Still appears that conditions will
drop to IFR or low MVFR within 1-3 hours after the onset of the
snow. KUIN will see the onset of snow around 12Z. Accumulations of
snow is still expected to be around 1 inch at KCOU and less at
KUIN and the St. Louis metro TAF sites. The snow will switch over
to drizzle during the afternoon before ending by late in the
afternoon. IFR or low MVFR ceilings are expected through the end
of the period.

Specifics for KSTL: Snow is expected to move into the terminal
after 09Z with VFR conditions initially given dry air in the
atmosphere. IFR conditions and steady snow is expected by 14Z with
an accumulation of less than 1 inch. The snow should switch over
to drizzle by 18Z with IFR ceilings lasting through the rest of
the TAF period.

Britt

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     36  28  37  29 /  80   5   5  10
Quincy          33  25  33  27 /  80   5   5   5
Columbia        36  30  37  30 /  80  10   5  10
Jefferson City  37  29  38  31 /  70  10  10  10
Salem           36  27  37  26 /  40   5   5  20
Farmington      36  28  37  26 /  70  10   5  20

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...WINTER WEATHER ADVISORY until 10 AM CST this morning FOR Boone
     MO-Callaway MO-Cole MO-Crawford MO-Gasconade MO-Iron MO-
     Madison MO-Moniteau MO-Osage MO-Reynolds MO-St. Francois MO-
     Washington MO.

IL...NONE.
&&

$$

WFO LSX






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